xref: /csrg-svn/sbin/dump/traverse.c (revision 54596)
147082Smckusick /*-
247082Smckusick  * Copyright (c) 1980, 1988, 1991 The Regents of the University of California.
347082Smckusick  * All rights reserved.
447082Smckusick  *
547082Smckusick  * %sccs.include.redist.c%
622041Sdist  */
75329Smckusic 
822041Sdist #ifndef lint
9*54596Smckusick static char sccsid[] = "@(#)traverse.c	5.19 (Berkeley) 07/02/92";
1046584Storek #endif /* not lint */
1122041Sdist 
1250499Smckusick #ifdef sunos
1350499Smckusick #include <stdio.h>
1450499Smckusick #include <ctype.h>
1546795Sbostic #include <sys/param.h>
1651605Sbostic #include <ufs/fs.h>
1750499Smckusick #else
1850499Smckusick #include <sys/param.h>
1954070Smckusick #include <ufs/ffs/fs.h>
2054070Smckusick #endif
2153657Smckusick #include <sys/time.h>
2254070Smckusick #include <sys/stat.h>
2351605Sbostic #include <ufs/ufs/dir.h>
2451605Sbostic #include <ufs/ufs/dinode.h>
2546795Sbostic #include <protocols/dumprestore.h>
2646795Sbostic #ifdef __STDC__
2746795Sbostic #include <unistd.h>
2846795Sbostic #include <string.h>
2946795Sbostic #endif
301426Sroot #include "dump.h"
311426Sroot 
3246792Smckusick void	dmpindir();
3346792Smckusick #define	HASDUMPEDFILE	0x1
3446792Smckusick #define	HASSUBDIRS	0x2
3546584Storek 
3646584Storek /*
3746584Storek  * This is an estimation of the number of TP_BSIZE blocks in the file.
3846584Storek  * It estimates the number of blocks in files with holes by assuming
3946584Storek  * that all of the blocks accounted for by di_blocks are data blocks
4046584Storek  * (when some of the blocks are usually used for indirect pointers);
4146584Storek  * hence the estimate may be high.
4246584Storek  */
4346792Smckusick long
4447058Smckusick blockest(dp)
4547058Smckusick 	register struct dinode *dp;
4646584Storek {
4746792Smckusick 	long blkest, sizeest;
4846584Storek 
4946584Storek 	/*
5047058Smckusick 	 * dp->di_size is the size of the file in bytes.
5147058Smckusick 	 * dp->di_blocks stores the number of sectors actually in the file.
5246584Storek 	 * If there are more sectors than the size would indicate, this just
5346584Storek 	 *	means that there are indirect blocks in the file or unused
5446584Storek 	 *	sectors in the last file block; we can safely ignore these
5546792Smckusick 	 *	(blkest = sizeest below).
5646584Storek 	 * If the file is bigger than the number of sectors would indicate,
5746584Storek 	 *	then the file has holes in it.	In this case we must use the
5846584Storek 	 *	block count to estimate the number of data blocks used, but
5946584Storek 	 *	we use the actual size for estimating the number of indirect
6046792Smckusick 	 *	dump blocks (sizeest vs. blkest in the indirect block
6146792Smckusick 	 *	calculation).
6246584Storek 	 */
6347058Smckusick 	blkest = howmany(dbtob(dp->di_blocks), TP_BSIZE);
6447058Smckusick 	sizeest = howmany(dp->di_size, TP_BSIZE);
6546792Smckusick 	if (blkest > sizeest)
6646792Smckusick 		blkest = sizeest;
6747058Smckusick 	if (dp->di_size > sblock->fs_bsize * NDADDR) {
6846584Storek 		/* calculate the number of indirect blocks on the dump tape */
6946792Smckusick 		blkest +=
7046792Smckusick 			howmany(sizeest - NDADDR * sblock->fs_bsize / TP_BSIZE,
7146584Storek 			TP_NINDIR);
7246584Storek 	}
7346792Smckusick 	return (blkest + 1);
7446584Storek }
7546584Storek 
7646792Smckusick /*
7746792Smckusick  * Dump pass 1.
7846792Smckusick  *
7946792Smckusick  * Walk the inode list for a filesystem to find all allocated inodes
8046792Smckusick  * that have been modified since the previous dump time. Also, find all
8146792Smckusick  * the directories in the filesystem.
8246792Smckusick  */
8346792Smckusick mapfiles(maxino, tapesize)
8446792Smckusick 	ino_t maxino;
8546792Smckusick 	long *tapesize;
8646584Storek {
8746792Smckusick 	register int mode;
8846792Smckusick 	register ino_t ino;
8946792Smckusick 	register struct dinode *dp;
9046792Smckusick 	int anydirskipped = 0;
9146584Storek 
9246792Smckusick 	for (ino = 0; ino < maxino; ino++) {
9346792Smckusick 		dp = getino(ino);
9446792Smckusick 		if ((mode = (dp->di_mode & IFMT)) == 0)
9546792Smckusick 			continue;
9646792Smckusick 		SETINO(ino, usedinomap);
9746792Smckusick 		if (mode == IFDIR)
9846792Smckusick 			SETINO(ino, dumpdirmap);
9954070Smckusick 		if ((dp->di_mtime.ts_sec >= spcl.c_ddate ||
10054070Smckusick 		    dp->di_ctime.ts_sec >= spcl.c_ddate)
10154070Smckusick #ifndef sunos
10254070Smckusick 		    && (dp->di_flags & NODUMP) != NODUMP
10354070Smckusick #endif
10454070Smckusick 		    ) {
10546792Smckusick 			SETINO(ino, dumpinomap);
10646792Smckusick 			if (mode != IFREG && mode != IFDIR && mode != IFLNK) {
10746792Smckusick 				*tapesize += 1;
10846792Smckusick 				continue;
10946792Smckusick 			}
11046792Smckusick 			*tapesize += blockest(dp);
11146792Smckusick 			continue;
11246792Smckusick 		}
11346792Smckusick 		if (mode == IFDIR)
11446792Smckusick 			anydirskipped = 1;
11546792Smckusick 	}
11646792Smckusick 	/*
11746792Smckusick 	 * Restore gets very upset if the root is not dumped,
11846792Smckusick 	 * so ensure that it always is dumped.
11946792Smckusick 	 */
12051374Smckusick 	SETINO(ROOTINO, dumpinomap);
12146792Smckusick 	return (anydirskipped);
12246584Storek }
12346584Storek 
12446792Smckusick /*
12546792Smckusick  * Dump pass 2.
12646792Smckusick  *
12746792Smckusick  * Scan each directory on the filesystem to see if it has any modified
12846792Smckusick  * files in it. If it does, and has not already been added to the dump
12946792Smckusick  * list (because it was itself modified), then add it. If a directory
13046792Smckusick  * has not been modified itself, contains no modified files and has no
13146792Smckusick  * subdirectories, then it can be deleted from the dump list and from
13246792Smckusick  * the list of directories. By deleting it from the list of directories,
13346792Smckusick  * its parent may now qualify for the same treatment on this or a later
13446792Smckusick  * pass using this algorithm.
13546792Smckusick  */
13646792Smckusick mapdirs(maxino, tapesize)
13746792Smckusick 	ino_t maxino;
13846792Smckusick 	long *tapesize;
13946792Smckusick {
14046792Smckusick 	register struct	dinode *dp;
14147058Smckusick 	register int i, dirty;
14225797Smckusick 	register char *map;
14346792Smckusick 	register ino_t ino;
14454070Smckusick 	long filesize;
14546792Smckusick 	int ret, change = 0;
1461426Sroot 
14746792Smckusick 	for (map = dumpdirmap, ino = 0; ino < maxino; ) {
14846584Storek 		if ((ino % NBBY) == 0)
14947058Smckusick 			dirty = *map++;
15046792Smckusick 		else
15147058Smckusick 			dirty >>= 1;
1524702Smckusic 		ino++;
15347058Smckusick 		if ((dirty & 1) == 0 || TSTINO(ino, dumpinomap))
15446792Smckusick 			continue;
15546792Smckusick 		dp = getino(ino);
15646792Smckusick 		filesize = dp->di_size;
15746792Smckusick 		for (ret = 0, i = 0; filesize > 0 && i < NDADDR; i++) {
15846792Smckusick 			if (dp->di_db[i] != 0)
15946792Smckusick 				ret |= searchdir(ino, dp->di_db[i],
16046796Smckusick 					dblksize(sblock, dp, i), filesize);
16146792Smckusick 			if (ret & HASDUMPEDFILE)
16246792Smckusick 				filesize = 0;
16346792Smckusick 			else
16446792Smckusick 				filesize -= sblock->fs_bsize;
16546792Smckusick 		}
16646792Smckusick 		for (i = 0; filesize > 0 && i < NIADDR; i++) {
16746792Smckusick 			if (dp->di_ib[i] == 0)
16846792Smckusick 				continue;
16946792Smckusick 			ret |= dirindir(ino, dp->di_ib[i], i, &filesize);
17046792Smckusick 		}
17146792Smckusick 		if (ret & HASDUMPEDFILE) {
17246792Smckusick 			if (!TSTINO(ino, dumpinomap)) {
17346792Smckusick 				SETINO(ino, dumpinomap);
17446792Smckusick 				*tapesize += blockest(dp);
17546792Smckusick 			}
17646792Smckusick 			change = 1;
17746792Smckusick 			continue;
17846792Smckusick 		}
17946792Smckusick 		if ((ret & HASSUBDIRS) == 0) {
18046792Smckusick 			if (!TSTINO(ino, dumpinomap)) {
18146792Smckusick 				CLRINO(ino, dumpdirmap);
18246792Smckusick 				change = 1;
18346792Smckusick 			}
18446792Smckusick 		}
1851426Sroot 	}
18646792Smckusick 	return (change);
1871426Sroot }
1881426Sroot 
18946792Smckusick /*
19046792Smckusick  * Read indirect blocks, and pass the data blocks to be searched
19146792Smckusick  * as directories. Quit as soon as any entry is found that will
19246792Smckusick  * require the directory to be dumped.
19346792Smckusick  */
19454070Smckusick dirindir(ino, blkno, ind_level, filesize)
19546792Smckusick 	ino_t ino;
19646792Smckusick 	daddr_t blkno;
19754070Smckusick 	int ind_level;
19854070Smckusick 	long *filesize;
1991426Sroot {
20046792Smckusick 	int ret = 0;
20146792Smckusick 	register int i;
20246792Smckusick 	daddr_t	idblk[MAXNINDIR];
2031426Sroot 
20454070Smckusick 	bread(fsbtodb(sblock, blkno), (char *)idblk, (int)sblock->fs_bsize);
20554070Smckusick 	if (ind_level <= 0) {
20646792Smckusick 		for (i = 0; *filesize > 0 && i < NINDIR(sblock); i++) {
20746792Smckusick 			blkno = idblk[i];
20846792Smckusick 			if (blkno != 0)
20946796Smckusick 				ret |= searchdir(ino, blkno, sblock->fs_bsize,
21054070Smckusick 					*filesize);
21146792Smckusick 			if (ret & HASDUMPEDFILE)
21246792Smckusick 				*filesize = 0;
21346792Smckusick 			else
21446792Smckusick 				*filesize -= sblock->fs_bsize;
2151426Sroot 		}
21646792Smckusick 		return (ret);
2175329Smckusic 	}
21854070Smckusick 	ind_level--;
21946792Smckusick 	for (i = 0; *filesize > 0 && i < NINDIR(sblock); i++) {
22046792Smckusick 		blkno = idblk[i];
22146792Smckusick 		if (blkno != 0)
22254070Smckusick 			ret |= dirindir(ino, blkno, ind_level, filesize);
2235329Smckusic 	}
22446792Smckusick 	return (ret);
2251426Sroot }
2261426Sroot 
22746792Smckusick /*
22846792Smckusick  * Scan a disk block containing directory information looking to see if
22946792Smckusick  * any of the entries are on the dump list and to see if the directory
23046792Smckusick  * contains any subdirectories.
23146792Smckusick  */
23246796Smckusick searchdir(ino, blkno, size, filesize)
23346792Smckusick 	ino_t ino;
23446792Smckusick 	daddr_t blkno;
23554070Smckusick 	register long size;
23654070Smckusick 	long filesize;
2375329Smckusic {
23846792Smckusick 	register struct direct *dp;
23946792Smckusick 	register long loc;
24046792Smckusick 	char dblk[MAXBSIZE];
2415329Smckusic 
24254070Smckusick 	bread(fsbtodb(sblock, blkno), dblk, (int)size);
24346796Smckusick 	if (filesize < size)
24446796Smckusick 		size = filesize;
24546792Smckusick 	for (loc = 0; loc < size; ) {
24646792Smckusick 		dp = (struct direct *)(dblk + loc);
24746792Smckusick 		if (dp->d_reclen == 0) {
24846792Smckusick 			msg("corrupted directory, inumber %d\n", ino);
24946792Smckusick 			break;
2505329Smckusic 		}
25146792Smckusick 		loc += dp->d_reclen;
25246792Smckusick 		if (dp->d_ino == 0)
25346792Smckusick 			continue;
25446792Smckusick 		if (dp->d_name[0] == '.') {
25546792Smckusick 			if (dp->d_name[1] == '\0')
25646792Smckusick 				continue;
25746792Smckusick 			if (dp->d_name[1] == '.' && dp->d_name[2] == '\0')
25846792Smckusick 				continue;
2595329Smckusic 		}
26046792Smckusick 		if (TSTINO(dp->d_ino, dumpinomap))
26146792Smckusick 			return (HASDUMPEDFILE);
26246792Smckusick 		if (TSTINO(dp->d_ino, dumpdirmap))
26346792Smckusick 			return (HASSUBDIRS);
2645329Smckusic 	}
26546792Smckusick 	return (0);
2665329Smckusic }
2675329Smckusic 
26846792Smckusick /*
26946792Smckusick  * Dump passes 3 and 4.
27046792Smckusick  *
27146792Smckusick  * Dump the contents of an inode to tape.
27246792Smckusick  */
27346584Storek void
27447058Smckusick dumpino(dp, ino)
27547058Smckusick 	register struct dinode *dp;
27646792Smckusick 	ino_t ino;
27717234Smckusick {
278*54596Smckusick 	int ind_level, cnt;
2794777Smckusic 	long size;
280*54596Smckusick 	char buf[TP_BSIZE];
2811426Sroot 
28246792Smckusick 	if (newtape) {
2831426Sroot 		newtape = 0;
28446792Smckusick 		dumpmap(dumpinomap, TS_BITS, ino);
2851426Sroot 	}
28646792Smckusick 	CLRINO(ino, dumpinomap);
28747058Smckusick 	spcl.c_dinode = *dp;
2881426Sroot 	spcl.c_type = TS_INODE;
2891426Sroot 	spcl.c_count = 0;
290*54596Smckusick 	switch (IFTODT(dp->di_mode)) {
291*54596Smckusick 
292*54596Smckusick 	case DT_UNKNOWN:
293*54596Smckusick 		/*
294*54596Smckusick 		 * Freed inode.
295*54596Smckusick 		 */
29617234Smckusick 		return;
297*54596Smckusick 
298*54596Smckusick 	case DT_LNK:
299*54596Smckusick 		/*
300*54596Smckusick 		 * Check for short symbolic link.
301*54596Smckusick 		 */
302*54596Smckusick 		if (dp->di_size > 0 &&
303*54596Smckusick 		    dp->di_size < sblock->fs_maxsymlinklen) {
304*54596Smckusick 			spcl.c_addr[0] = 1;
305*54596Smckusick 			spcl.c_count = 1;
306*54596Smckusick 			writeheader(ino);
307*54596Smckusick 			bcopy((caddr_t)dp->di_shortlink, buf,
308*54596Smckusick 			    (u_long)dp->di_size);
309*54596Smckusick 			buf[dp->di_size] = '\0';
310*54596Smckusick 			writerec(buf, 0);
311*54596Smckusick 			return;
312*54596Smckusick 		}
313*54596Smckusick 		/* fall through */
314*54596Smckusick 
315*54596Smckusick 	case DT_DIR:
316*54596Smckusick 	case DT_REG:
317*54596Smckusick 		if (dp->di_size > 0)
318*54596Smckusick 			break;
319*54596Smckusick 		/* fall through */
320*54596Smckusick 
321*54596Smckusick 	case DT_FIFO:
322*54596Smckusick 	case DT_SOCK:
323*54596Smckusick 	case DT_CHR:
324*54596Smckusick 	case DT_BLK:
32546792Smckusick 		writeheader(ino);
3261426Sroot 		return;
327*54596Smckusick 
328*54596Smckusick 	default:
329*54596Smckusick 		msg("Warning: undefined file type 0%o\n", dp->di_mode & IFMT);
330*54596Smckusick 		return;
3311426Sroot 	}
33247058Smckusick 	if (dp->di_size > NDADDR * sblock->fs_bsize)
33346792Smckusick 		cnt = NDADDR * sblock->fs_frag;
3344777Smckusic 	else
33547058Smckusick 		cnt = howmany(dp->di_size, sblock->fs_fsize);
33647058Smckusick 	blksout(&dp->di_db[0], cnt, ino);
33747058Smckusick 	if ((size = dp->di_size - NDADDR * sblock->fs_bsize) <= 0)
3384777Smckusic 		return;
33954070Smckusick 	for (ind_level = 0; ind_level < NIADDR; ind_level++) {
34054070Smckusick 		dmpindir(ino, dp->di_ib[ind_level], ind_level, &size);
3414777Smckusic 		if (size <= 0)
3424777Smckusic 			return;
3434777Smckusic 	}
3441426Sroot }
3451426Sroot 
34646792Smckusick /*
34746792Smckusick  * Read indirect blocks, and pass the data blocks to be dumped.
34846792Smckusick  */
34946584Storek void
35054070Smckusick dmpindir(ino, blk, ind_level, size)
35146792Smckusick 	ino_t ino;
3524777Smckusic 	daddr_t blk;
35354070Smckusick 	int ind_level;
3544777Smckusic 	long *size;
3551426Sroot {
3564777Smckusic 	int i, cnt;
3575329Smckusic 	daddr_t idblk[MAXNINDIR];
3581426Sroot 
3594777Smckusic 	if (blk != 0)
36054070Smckusick 		bread(fsbtodb(sblock, blk), (char *)idblk, (int) sblock->fs_bsize);
3614777Smckusic 	else
36254070Smckusick 		bzero((char *)idblk, (int)sblock->fs_bsize);
36354070Smckusick 	if (ind_level <= 0) {
3645329Smckusic 		if (*size < NINDIR(sblock) * sblock->fs_bsize)
3655329Smckusic 			cnt = howmany(*size, sblock->fs_fsize);
3664777Smckusic 		else
3675329Smckusic 			cnt = NINDIR(sblock) * sblock->fs_frag;
3685329Smckusic 		*size -= NINDIR(sblock) * sblock->fs_bsize;
36946792Smckusick 		blksout(&idblk[0], cnt, ino);
3704777Smckusic 		return;
3711426Sroot 	}
37254070Smckusick 	ind_level--;
3735329Smckusic 	for (i = 0; i < NINDIR(sblock); i++) {
37454070Smckusick 		dmpindir(ino, idblk[i], ind_level, size);
3754777Smckusic 		if (*size <= 0)
3764777Smckusic 			return;
3774777Smckusic 	}
3781426Sroot }
3791426Sroot 
38046792Smckusick /*
38146792Smckusick  * Collect up the data into tape record sized buffers and output them.
38246792Smckusick  */
38346584Storek void
38446792Smckusick blksout(blkp, frags, ino)
3854777Smckusic 	daddr_t *blkp;
3864777Smckusic 	int frags;
38746792Smckusick 	ino_t ino;
3884777Smckusic {
38946584Storek 	register daddr_t *bp;
3905329Smckusic 	int i, j, count, blks, tbperdb;
3914777Smckusic 
3929403Smckusick 	blks = howmany(frags * sblock->fs_fsize, TP_BSIZE);
39346584Storek 	tbperdb = sblock->fs_bsize >> tp_bshift;
3944777Smckusic 	for (i = 0; i < blks; i += TP_NINDIR) {
3954777Smckusic 		if (i + TP_NINDIR > blks)
3964777Smckusic 			count = blks;
3974777Smckusic 		else
3984777Smckusic 			count = i + TP_NINDIR;
3994777Smckusic 		for (j = i; j < count; j++)
4005329Smckusic 			if (blkp[j / tbperdb] != 0)
4014777Smckusic 				spcl.c_addr[j - i] = 1;
4024777Smckusic 			else
4034777Smckusic 				spcl.c_addr[j - i] = 0;
4044777Smckusic 		spcl.c_count = count - i;
40546792Smckusick 		writeheader(ino);
40646584Storek 		bp = &blkp[i / tbperdb];
40746584Storek 		for (j = i; j < count; j += tbperdb, bp++)
40846584Storek 			if (*bp != 0)
4095329Smckusic 				if (j + tbperdb <= count)
41054070Smckusick 					dumpblock(*bp, (int)sblock->fs_bsize);
4114777Smckusic 				else
41246792Smckusick 					dumpblock(*bp, (count - j) * TP_BSIZE);
4134777Smckusic 		spcl.c_type = TS_ADDR;
4144777Smckusic 	}
4154777Smckusic }
4164777Smckusic 
41746792Smckusick /*
41846792Smckusick  * Dump a map to the tape.
41946792Smckusick  */
42046584Storek void
42146792Smckusick dumpmap(map, type, ino)
4225329Smckusic 	char *map;
42346792Smckusick 	int type;
42446792Smckusick 	ino_t ino;
4251426Sroot {
42646792Smckusick 	register int i;
4271426Sroot 	char *cp;
4281426Sroot 
42946792Smckusick 	spcl.c_type = type;
43046792Smckusick 	spcl.c_count = howmany(mapsize * sizeof(char), TP_BSIZE);
43146792Smckusick 	writeheader(ino);
4325329Smckusic 	for (i = 0, cp = map; i < spcl.c_count; i++, cp += TP_BSIZE)
433*54596Smckusick 		writerec(cp, 0);
4341426Sroot }
4351426Sroot 
43646792Smckusick /*
43746792Smckusick  * Write a header record to the dump tape.
43846792Smckusick  */
43946584Storek void
44046792Smckusick writeheader(ino)
44146792Smckusick 	ino_t ino;
4421426Sroot {
44346792Smckusick 	register long sum, cnt, *lp;
4441426Sroot 
4451426Sroot 	spcl.c_inumber = ino;
4468368Smckusick 	spcl.c_magic = NFS_MAGIC;
4471426Sroot 	spcl.c_checksum = 0;
44846792Smckusick 	lp = (long *)&spcl;
44946792Smckusick 	sum = 0;
45046792Smckusick 	cnt = sizeof(union u_spcl) / (4 * sizeof(long));
45146792Smckusick 	while (--cnt >= 0) {
45246792Smckusick 		sum += *lp++;
45346792Smckusick 		sum += *lp++;
45446792Smckusick 		sum += *lp++;
45546792Smckusick 		sum += *lp++;
45624168Smckusick 	}
45746792Smckusick 	spcl.c_checksum = CHECKSUM - sum;
458*54596Smckusick 	writerec((char *)&spcl, 1);
4591426Sroot }
4601426Sroot 
4614702Smckusic struct dinode *
46246792Smckusick getino(inum)
46346792Smckusick 	ino_t inum;
4644702Smckusic {
4654702Smckusic 	static daddr_t minino, maxino;
46646792Smckusick 	static struct dinode inoblock[MAXINOPB];
4674702Smckusic 
46846792Smckusick 	curino = inum;
46946792Smckusick 	if (inum >= minino && inum < maxino)
47046792Smckusick 		return (&inoblock[inum - minino]);
47154070Smckusick 	bread(fsbtodb(sblock, itod(sblock, inum)), (char *)inoblock,
47254070Smckusick 	    (int)sblock->fs_bsize);
47346792Smckusick 	minino = inum - (inum % INOPB(sblock));
4745329Smckusic 	maxino = minino + INOPB(sblock);
47546792Smckusick 	return (&inoblock[inum - minino]);
4764702Smckusic }
4774702Smckusic 
47846792Smckusick /*
47946792Smckusick  * Read a chunk of data from the disk.
48046792Smckusick  * Try to recover from hard errors by reading in sector sized pieces.
48146792Smckusick  * Error recovery is attempted at most BREADEMAX times before seeking
48246792Smckusick  * consent from the operator to continue.
48346792Smckusick  */
4841426Sroot int	breaderrors = 0;
4851426Sroot #define	BREADEMAX 32
4861426Sroot 
48746584Storek void
48846792Smckusick bread(blkno, buf, size)
48946792Smckusick 	daddr_t blkno;
49046792Smckusick 	char *buf;
49146792Smckusick 	int size;
4921426Sroot {
49346792Smckusick 	int cnt, i;
49434359Skarels 	extern int errno;
4951426Sroot 
49615095Smckusick loop:
49754070Smckusick 	if ((int)lseek(diskfd, ((off_t)blkno << dev_bshift), 0) < 0)
4981426Sroot 		msg("bread: lseek fails\n");
49946792Smckusick 	if ((cnt = read(diskfd, buf, size)) == size)
50015095Smckusick 		return;
50146792Smckusick 	if (blkno + (size / dev_bsize) > fsbtodb(sblock, sblock->fs_size)) {
50215095Smckusick 		/*
50315095Smckusick 		 * Trying to read the final fragment.
50415095Smckusick 		 *
50515095Smckusick 		 * NB - dump only works in TP_BSIZE blocks, hence
50630560Smckusick 		 * rounds `dev_bsize' fragments up to TP_BSIZE pieces.
50715095Smckusick 		 * It should be smarter about not actually trying to
50815095Smckusick 		 * read more than it can get, but for the time being
50915095Smckusick 		 * we punt and scale back the read only when it gets
51015095Smckusick 		 * us into trouble. (mkm 9/25/83)
51115095Smckusick 		 */
51246792Smckusick 		size -= dev_bsize;
51315095Smckusick 		goto loop;
5141426Sroot 	}
51550905Smckusick 	if (cnt == -1)
51650905Smckusick 		msg("read error from %s: %s: [block %d]: count=%d\n",
51750905Smckusick 			disk, strerror(errno), blkno, size);
51850905Smckusick 	else
51950905Smckusick 		msg("short read error from %s: [block %d]: count=%d, got=%d\n",
52050905Smckusick 			disk, blkno, size, cnt);
52146584Storek 	if (++breaderrors > BREADEMAX) {
52215095Smckusick 		msg("More than %d block read errors from %d\n",
52315095Smckusick 			BREADEMAX, disk);
52415095Smckusick 		broadcast("DUMP IS AILING!\n");
52515095Smckusick 		msg("This is an unrecoverable error.\n");
52615095Smckusick 		if (!query("Do you want to attempt to continue?")){
52715095Smckusick 			dumpabort();
52815095Smckusick 			/*NOTREACHED*/
52915095Smckusick 		} else
53015095Smckusick 			breaderrors = 0;
53115095Smckusick 	}
53234359Skarels 	/*
53334359Skarels 	 * Zero buffer, then try to read each sector of buffer separately.
53434359Skarels 	 */
53546792Smckusick 	bzero(buf, size);
53646792Smckusick 	for (i = 0; i < size; i += dev_bsize, buf += dev_bsize, blkno++) {
53754070Smckusick 		if ((int)lseek(diskfd, ((off_t)blkno << dev_bshift), 0) < 0)
53834359Skarels 			msg("bread: lseek2 fails!\n");
53954070Smckusick 		if ((cnt = read(diskfd, buf, (int)dev_bsize)) == dev_bsize)
54050905Smckusick 			continue;
54150905Smckusick 		if (cnt == -1) {
54250905Smckusick 			msg("read error from %s: %s: [sector %d]: count=%d\n",
54350905Smckusick 				disk, strerror(errno), blkno, dev_bsize);
54450905Smckusick 			continue;
54550905Smckusick 		}
54650905Smckusick 		msg("short read error from %s: [sector %d]: count=%d, got=%d\n",
54750905Smckusick 			disk, blkno, dev_bsize, cnt);
54834359Skarels 	}
5491426Sroot }
550